The presence of weeds in the culture of pupunha is one of the factors that reduce its growth and its productivity. The use of selective herbicide can be a viable solution. However, little is known regarding the selectivity of herbicide, not even products registered for the culture in the national market exist. However the active ingredient glyphosate is widely used by producers of pupunha in the Valley of the Ribeira. The phosphite of potassium acts as an activator of the production of shikimic acid, it is expected that the same it acts as safener, protecting the cultures of the fitotóxico effect provoked by the same drift or for the application of the active ingredient glyphosate. The work has as objective to verify the protective action of the phosphite of potassium in the poisoning generated by the application of doses of the herbicide glyphosate in changes of pupunha, as to contribute with the established strategies of handling already set for the culture in the region of the Valley of the Ribeira/SP. Three doses of the equivalent herbicideglyphosate acid will be tested (full dose indicated by the manufacturer, half a dose and ¼ of the dose), isolated or in association to the phosphite, the 3 L/ha, which will be applied bimonthly during the first year of implantation of the culture in the field. The evaluations of phytopoisoning of the plants of pupunha will be carried through on the 30, 60, 90, 120 and 180 days of the application of the treatment. At the same times, it will be determined some biometrichy variable such as: height of the plants, diameter of the colon and size of leaf one. In the occasion, it will also be collected one gram of cool material for biochemist analysis of the organic composition shikimato. The adopted experimental delineation will be of blocks casualized with four repetitions. The results will be submitted to the analysis of variance for test “F” and the averages of the treatments compared by the test “t” to 5% of the probability for the variable phytointoxication and biometry. The data of the biochemist analysis will be submitted to the calculations of the cumulative frequencies in function of the relation of the accumulation of shiquimato and the dose of the herbicide, for the model of Gompertz adopting the original data, evaluating the level of precision for the determination coefficient (R2) and the value of F.
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